U.S. patent application number 11/835060 was filed with the patent office on 2008-02-21 for profile forming method, profile forming program, and printing system.
This patent application is currently assigned to CANON KABUSHIKI KAISHA. Invention is credited to Yingying Fan, Mizue Misumi, Hiromitsu Nishikawa, Kazuhiro Saito.
Application Number | 20080043266 11/835060 |
Document ID | / |
Family ID | 38657304 |
Filed Date | 2008-02-21 |
United States Patent
Application |
20080043266 |
Kind Code |
A1 |
Misumi; Mizue ; et
al. |
February 21, 2008 |
PROFILE FORMING METHOD, PROFILE FORMING PROGRAM, AND PRINTING
SYSTEM
Abstract
A profile forming method includes a category obtaining step of
obtaining a category of a printing medium, a profile obtaining step
of obtaining a profile corresponding to the category of the
printing medium, a total colorant amount obtaining step of
obtaining a total colorant amount corresponding to the printing
medium, and a profile forming step of forming another profile
adapted for the printing medium based on both the profile obtained
in the profile obtaining step and the total colorant amount.
Inventors: |
Misumi; Mizue;
(Utsunomiya-shi, JP) ; Saito; Kazuhiro;
(Yokohama-shi, JP) ; Nishikawa; Hiromitsu; (Tokyo,
JP) ; Fan; Yingying; (Tokyo, JP) |
Correspondence
Address: |
CANON U.S.A. INC. INTELLECTUAL PROPERTY DIVISION
15975 ALTON PARKWAY
IRVINE
CA
92618-3731
US
|
Assignee: |
CANON KABUSHIKI KAISHA
30-2, Shimomaruko 3-Chome, Ohta-ku
Tokyo
JP
146-8501
|
Family ID: |
38657304 |
Appl. No.: |
11/835060 |
Filed: |
August 7, 2007 |
Current U.S.
Class: |
358/1.9 |
Current CPC
Class: |
H04N 1/6016 20130101;
H04N 1/603 20130101; H04N 1/6097 20130101 |
Class at
Publication: |
358/001.9 |
International
Class: |
H04N 1/60 20060101
H04N001/60 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 8, 2006 |
JP |
2006-215858 |
Jun 28, 2007 |
JP |
2007-170230 |
Claims
1. A profile forming method for use in an image forming system,
comprising: obtaining a category of a printing medium; obtaining a
profile corresponding to the category of the printing medium;
obtaining a total colorant amount corresponding to the printing
medium; and forming another profile adapted for the printing medium
based on both the profile obtained in the profile obtaining step
and the total colorant amount.
2. A method as claimed in claim 1, wherein the category of printing
medium is at least one member of the group consisting of glossy
paper, art paper, and plain paper.
3. A method as claimed in claim 1, wherein the printing medium has
a different color development characteristic for each category of
the printing medium.
4. A method as claimed in claim 1, wherein the printing medium has
a different total colorant amount for each category of the printing
medium.
5. A method as claimed in claim 4, wherein the profile differs for
each category of the printing medium.
6. A method as claimed in claim 1, wherein the profile differs
according to printing quality.
7. A method as claimed in claim 1, wherein the profile differs for
each kind of colorant.
8. A method as claimed in claim 1, wherein the profile is a color
separation profile for color separation of input data to a signal
for a colorant used in a printing apparatus.
9. A method as claimed in claim 8, wherein the color separation
profile differs in usage of the colorant depending on the category
of the printing medium.
10. A method as claimed in claim 9, wherein the color separation
profile is a lookup table storing the signal for the colorant for
each grid point distributed over a grid of an RGB three-dimensional
cube.
11. A method as claimed in claim 10, wherein the profile forming
step forms the other profile by calculating a colorant amount on
each of a plurality of frame lines, which are defined as lines
which interconnect apexes of the RGB three-dimensional cube.
12. A method as claimed in claim 1, wherein the profile includes a
color matching profile for making a color gamut of input data and a
color gamut of a printing apparatus corresponding to each other,
and a color separation profile for color separation of the input
data to a signal for a colorant used in the printing apparatus.
13. A method as claimed in claim 1, wherein the total colorant
amount is a colorant amount acceptable to the printing medium.
14. A method as claimed in claim 1, wherein the total colorant
amount is decided based on an arbitrary input numerical value.
15. A method as claimed in claim 1, wherein the profile forming
step forms the other profile by correcting the profile obtained in
the profile obtaining step such that the total colorant amount is
maintained.
16. A method as claimed in claim 1, wherein the profile forming
step forms the other profile with importance placed on graininess
and color reproduction.
17. A method as claimed in claim 1, wherein the profile forming
step forms the other profile based on the kind and usage of the
colorant.
18. A method as claimed in claim 1, further comprising: obtaining
light source information; and converting the obtained profile based
on the light source information.
19. A method as claimed in claim 1, further comprising: a color
gamut obtaining step of obtaining a color gamut of the printing
apparatus based on the other formed profile; a color matching
profile obtaining step of obtaining a color matching profile for
the profile obtaining in the profile obtaining step; and a color
matching profile forming step of forming a color matching profile
corresponding to the printing medium, as a printing target, based
on both the color gamut obtained in the color gamut obtaining step
and a color gamut conversion method obtained in the color matching
profile obtaining step.
20. A method as claimed in claim 19, wherein the color gamut
obtaining step comprises: a printing step of printing a color gamut
obtaining patch; and a calorimetric step of measuring colors of the
color gamut obtaining patch printed in the printing step, wherein a
color gamut of the other formed profile is obtained from results of
the color measurements executed in the calorimetric step.
21. A computer program which when loaded into a computer and
executed performs a method as claimed in claim 1.
22. A machine readable storage medium storing a program as claimed
in claim 21.
23. A printing system comprising: a category obtaining unit
configured to obtain a category of printing medium; a profile
obtaining unit configured to obtain a profile corresponding to the
category of the printing medium; a total colorant amount obtaining
unit configured to obtain a total colorant amount corresponding to
the printing medium; and a profile forming unit configured to form
another profile adapted for the printing medium based on both the
profile obtained by the profile obtaining unit and the total
colorant amount.
24. A printing system as claimed in claim 23, wherein the category
of printing medium is at least one member of the group consisting
of glossy paper, art paper, and plain paper.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a profile forming method, a
profile forming program, and a printing system.
[0003] 2. Description of the Related Art
[0004] Widespread use of digital still cameras and scanners has
increased opportunities for users to print images for artistic
appreciation and long-term storage. A demand for printing of images
in more desirable colors has also increased correspondingly. In
addition, development of printers toward higher resolution and
higher accuracy to be adapted for printing on larger-size paper,
for example, has increased opportunities that professional users,
such as graphic artists and photographers, employ printers as tools
for creating artistic works. Those professional users create works
by using various categories (types) of paper, including fine art
paper and thick paper. In order to meet demands of such
professional users, printer makers have increased the number of
categories of paper dedicated for the printers.
[0005] However, it is very difficult for printer makers to prepare
printer profiles adapted for all categories of paper demanded by
the users. Among commercially available paper, there are still many
categories of paper that are not yet specified to be adaptable by
the printer makers. Further, profiles of image output devices for
handling prints are generally formed based on a color reproduction
characteristic under standard illumination. Accordingly, the
profile prepared by the printer maker does not always reflect a
color reproduction characteristic appearing in an environment where
an output image is actually observed, and a satisfactory color
reproduction result cannot be obtained depending on the observation
environment.
[0006] When an image is printed out using paper not adapted for the
printer used, the following three major problems may occur. A first
problem is that, because a user's printing condition (combination
between the printer and the paper) is unknown, proper control
cannot be performed for a colorant amount, i.e., an amount of a
colorant, e.g., ink, which can be accepted by the paper as a target
for printing of the image. A second problem is that a color
development characteristic of the paper is unknown and optimum
color separation in consideration of the color development
characteristic cannot be performed. A third problem is that the
image cannot be printed out in a satisfactory color expected by the
user.
[0007] With the first one of the above-mentioned three problems,
i.e., incapability of performing the proper control of the colorant
amount, the following undesired results are caused. For example,
when the colorant amount is too much with respect to proper one,
scattering or a blur occurs due to ink that cannot be fully
accepted by the paper. When the colorant amount is too small with
respect to the proper one, a printable color range is limited and a
color reproduction range under the user's printing condition cannot
be effectively utilized.
[0008] With the second problem that the color development
characteristic of the paper is unknown and optimum color separation
cannot be performed, the following two drawbacks are caused. First,
the user is often obliged to observe discontinuity of color in,
e.g., a gradation image. Secondly, in spite of the paper being
selected by the user based on due consideration, characteristics of
the paper cannot be fully utilized. In general, the user selects
paper used for printing after imaging a work to be created by the
user. Therefore, the reproduction purpose is changed to a large
extent depending on the paper used in the work. The categories of
paper supported by the printer includes, e.g., glossy paper, art
paper, and plain paper. The glossy paper is suitable for printing a
photo in a satisfactory manner. The art paper is used to create an
artistic work without impairing the attractive specific feature of
the paper material. The plain paper is suitable for printing
general documents in a satisfactory manner. Stated another way,
using paper for which the profile is not prepared accompanies with
a possibility that the printing purpose depending on the paper is
not reliably achieved.
[0009] The above-described two problems are related to details of
printer control, and the solution of those problems generally
requires detailed study regarding the combination of printer and
paper, which should be conducted by a person having expert
knowledge with regards to printers. For that reason, it is very
difficult for a user not having the required expert knowledge to
overcome those two problems.
[0010] For the third problem--that the image cannot be printed out
in a color expected by the user--the user tries to realize a
desired tint primarily by using one of the following two methods.
The first method is to convert the image on a monitor to the
desired tint by using image retouch software, for example. The
second method is to adjust color processing of the printer by the
user so as to print the image in the desired tint. However, the
first method requires the user to learn the function and the
operation of the image retouch software and to perform color
conversion in consideration of both the color reproduction of the
monitor and the color reproduction of the printer. Thus, the first
method requires knowledge at a very high level. The second method
requires the user to learn the function and the operation of a
color-adjustment user interface which is provided by a printer
driver, and to have knowledge regarding the color reproduction of
the printer and general image processing. Stated another way, when
one of those two methods is employed, the user has to adjust the
tint by repeating the adjustment on a trial and error basis until a
print having the desired tint is obtained.
[0011] As described above, there is a demand for a system which is
easy to use even for a user not having expert knowledge with
regards to printers, and which can realize optimum printing for a
requested combination of printer and paper.
[0012] Japanese Patent Laid-Open No. 2001-346054 describes a
technique of forming a profile through the steps of obtaining an
ink duty value which is prepared in advance, and correcting the
existing profile based on the obtained ink duty value.
[0013] With the related art, however, because the color development
characteristic of a paper for which the profile is not prepared is
unknown and optimum color separation cannot be performed, there is
a possibility that the printing purpose to match with the paper is
not reliably achieved, or that the image cannot be printed out in a
color expected by the user.
SUMMARY OF THE INVENTION
[0014] The present invention enables an optimum profile to be
quickly formed for any category of printing medium. Also, the
present invention provides a profile forming method which can
obtain a satisfactory print even when a printer user prints an
image on a printing medium that is not supported in the printer
maker's specifications. The satisfactory print includes neither
scattering nor a blur of ink, keeps the user from observing a
discontinuity of color in, e.g., a gradation image, and ensures
color reproduction in a color expected by the user. In other words,
the obtained print reflects the color reproduction characteristic
appearing in an environment where an output image is actually
observed, and it realizes proper color reproduction regardless of
the observation environment.
[0015] According to one aspect of the present invention, a profile
forming method for use in an image forming system comprises
obtaining a category of a printing medium, obtaining a profile
corresponding to the category of the printing medium, obtaining a
total colorant amount corresponding to the printing medium, and
forming another profile adapted for the printing medium based on
both the profile obtained in the profile obtaining step and the
total colorant amount.
[0016] According to another aspect of the present invention, a
computer program performs profile forming method when loaded into a
computer and executed performs a method.
[0017] According to still another aspect of the present invention,
a machine readable storage medium stores the program.
[0018] According to still another aspect of the present invention,
a printing system comprises a category obtaining unit configured to
obtain a category of printing medium, a profile obtaining unit
configured to obtain a profile corresponding to the category of the
printing medium, a total colorant amount obtaining unit configured
to obtain a total colorant amount corresponding to the printing
medium, and a profile forming unit configured to form another
profile adapted for the printing medium based on both the profile
obtained by the profile obtaining unit and the total colorant
amount.
[0019] According to the present invention, an optimum profile can
be quickly formed for any category of printing medium.
[0020] Also, even when a printer user prints an image on a printing
medium that is not supported in the printer maker's specifications,
a satisfactory print can be obtained which includes neither
scattering nor a blur of ink, keeps the user from feeling
discontinuity of color in, e.g., a gradation image, and ensures
color reproduction in a satisfactory color expected by the
user.
[0021] Further features of the present invention will become
apparent from the following description of exemplary embodiments
with reference to the attached drawings, in which like reference
characters designate the same or similar parts throughout the
figures thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The accompanying drawings, which are incorporated in and
constitute a part of the specification, illustrate embodiments of
the invention and, together with the description, serve to explain
the principles of the invention.
[0023] FIG. 1 is a block diagram of an image printing system
according to a first embodiment of the present invention.
[0024] FIG. 2 is a flowchart showing a processing flow in the image
printing system according to the first embodiment.
[0025] FIG. 3 illustrates one example of a user interface for use
in a now profile forming process according to the first
embodiment.
[0026] FIG. 4 is a block diagram of a printer driver for use in the
image printing system according to the first embodiment of the
present invention.
[0027] FIG. 5 illustrates one example of a user interface for the
printer driver in the present invention.
[0028] FIG. 6 shows one exemplary list of paper categories in the
present invention.
[0029] FIG. 7 illustrates a data structure of a default profile
storage unit in the present invention.
[0030] FIG. 8 is a block diagram of an image printing system
according to a second embodiment of the present invention.
[0031] FIG. 9 is a block diagram of an image printing system
according to a third embodiment of the present invention.
[0032] FIG. 10 is a flowchart showing a flow of a total colorant
amount determining process in the present invention.
[0033] FIG. 11 illustrates one example of a total colorant amount
determining patch for use in the present invention.
[0034] FIG. 12 illustrates another example of the total colorant
amount determining patch for use in the present invention.
[0035] FIG. 13 is a flowchart showing a flow of a color separation
profile forming process in the present invention.
[0036] FIG. 14 is a flowchart showing a flow of a color matching
profile forming process in the present invention.
[0037] FIG. 15 is a graph showing one example of a color separation
profile for use in the present invention.
[0038] FIG. 16 is a graph showing another example of the color
separation profile for use in the present invention.
[0039] FIG. 17 is a graph showing one example of light source
information held in a light source information database.
[0040] FIG. 18 illustrates one example of a user interface for
setting details of light sources in a now profile forming process
according to the first embodiment.
[0041] FIG. 19 is a graph showing the relationship between
gradation change and category/usage of inks with respect to
printing quality.
[0042] FIG. 20 is a graph showing the relationship between
gradation change and category/usage of inks with respect to
printing quality.
DESCRIPTION OF THE EMBODIMENTS
[0043] Several embodiments of the present invention will be
described below in detail in accordance with the accompanying
drawings.
First Embodiment
[0044] A first embodiment of the present invention is now described
with reference to the drawings.
[0045] FIGS. 1 and 4 are block diagrams of an image printing system
according to the first embodiment of the present invention. The
image printing system includes a PC 101 for executing control, an
image display apparatus 102, such as a monitor, for displaying an
image, and an image forming apparatus 103, such as a printer, for
printing an image. Reference numeral 104 denotes a test chart
printed by the printer 103 using paper on which a user wants to
print an image. The test chart 104 is a print on which image data
is printed in, e.g 9 stages for each of RGB (729 colors in total).
Herein, the image data is desired to be capable of providing a
color reproduction characteristic under a printing environment
(including a printer and paper) in which the user wants to print an
image. The image printing system further includes a profile server
105 for supplying a printer profile to a printer driver via a
communication path, and an image input device 106, such as a
scanner, for inputting an image. The control PC 101 incorporates an
image processing application 107 for displaying and editing an
image on the PC 101, a printer driver 108 for controlling and
driving the printer 103, and an OS (Operating System) 109 for
operating the PC 101 itself. Reference numeral 110 denotes an
existing profile database holding printer/paper profile data that
is supported by the printer driver. Reference numeral 111 denotes a
light source information database holding spectral distribution
information of light sources which are expected to be used when
users observe prints.
[0046] Details of the light source information database 111 will
now be described with reference to FIG. 17. FIG. 17 is a graph
showing, by way of example, spectral distributions S(.lamda.) of
various light sources represented by D50, D65, A, C, F2, and F10
with respect to wavelength. It is here assumed that the light
source information database 111 holds the spectral distributions
S(.lamda.) shown in FIG. 17.
[0047] The existing profile database 110 has a data structure,
shown in FIG. 7, which holds three profiles for each of the printer
series, the model, the paper category, the printing quality, and
the matching method. Herein, the three profiles include a color
matching profile, a color separation profile, and a total colorant
amount. The reason why the profiles are prepared for each printer
model is that ink characteristics, the number of ink colors, the
amount of ejected ink, etc. differ from printer to printer. The
reason why the profiles are prepared for each paper category is
that, the number of kinds of inks, respective amounts of ink used,
and ratios of the inks used, etc. greatly differ for each paper
category even when the same printer is employed. FIGS. 15 and 16
show the ink amounts required in glossy paper, art paper, and plain
paper depending on gradation from green to black. More
specifically, FIG. 15 shows the ink amounts required for glossy
paper (FIG. 15A) and art paper (FIG. 15B), in which the maximum
colorant amount is the same as indicated by (1) and (1)', depending
on gradation from green to black. As seen from FIG. 15, the glossy
paper and the art paper employ the same ink colorants and the same
number of kinds of inks ((2) to (6) and (2)' to (6)'), but they
differ from each other in the usage of the inks (such as the ink
amounts and how the ink amounts are changed). In other words, since
the usage of the inks differs depending on the paper category, the
usage of the inks for each paper category can be effectively
selected by storing the existing profile for each paper category
and referring to the stored profile whenever a profile for a new
category of paper is formed. FIG. 16 shows the ink amounts required
for glossy paper (FIG. 16A) and plain paper (FIG. 16B) depending on
gradation from green to black. As seen from FIG. 16, five kinds of
inks (2) to (6) are used for the glossy paper, while only three
kinds of inks (4)', (5)' and (6)' are used for the plain paper. In
other words, since the number of kinds of ink differs depending on
the paper category, the kinds of ink to be used for each paper
category can be effectively selected by storing the existing
profile for each paper category and referring to the stored profile
whenever a profile for a new category of paper is formed.
[0048] The reason why the profiles are prepared for each item of
printing quality is that the kinds of inks and the usage of the
inks differ for each item of printing quality. There are plural
items of printing quality, such as "quick" and "fine". In an ink
jet printer, for example, the printing quality "quick" can be
improved by printing an image with one path so as to reduce the
number of paths required for printing of the entire printing medium
and/or by increasing the printing speed. In that case, because
larger amounts of inks are printed on the printing medium at a
time, there is a possibility of causing a phenomenon of the
so-called beading that adjacent dots are attracted to each other
and graininess appears in the printed image. This means the
necessity of setting the total colorant amount to a different value
for each item of printing quality. FIGS. 19 and 20 are graphs
showing the relationship between gradation change and
category/usage of inks with respect to printing quality "quick"
(FIG. 19) and "fine" (FIG. 20). In each graph, the horizontal axis
represents gradation change from white to red, and the vertical
axis represents the total colorant amount. In the printing quality
"quick" shown in FIG. 19, for example, the total colorant amount is
reduced as compared with the printing quality "fine", taking into
account the beading. In order to ensure a proper color density even
with the reduction of the total colorant amount, however, light ink
(Lm) is not used as one of the kinds of inks, and the amount of
dark ink (M) is increased in FIG. 19. Further, looking at the usage
of the inks, the dark ink starts to be used from near a value 1 of
the gradation. On the other hand, in the printing quality "fine"
shown in FIG. 20, the light ink (Lm) is also used as one of the
kinds of inks, and the total colorant amount is increased as
compared with the printing quality "quick" in FIG. 19 corresponding
to the reduction in printing speed. Further, looking at the usage
of the inks, the dark ink (M) starts to be used from near a value 4
of the gradation in consideration of the use of the light ink.
Thus, since the kinds of inks and the usage of the inks differ
depending on the printing quality, the kinds of inks and the usage
of the inks for each item of the printing quality can be
effectively utilized for a new profile, by preparing and storing
the profile that specifies the kinds of inks and the usage of the
inks for each item of the printing quality. Note that the printing
quality factor is not limited to the field of ink jet printers.
[0049] FIG. 4 is a block diagram showing details of the printer
driver 108 shown in FIG. 1. The printer driver 108 includes a
default profile storage section 401 for storing a color conversion
profile that is previously stored in the printer driver 108. The
printer driver 108 further includes a new profile forming and
processing section 402 for forming a new profile in conformity with
a user's requirements, and a new profile storing section 403 for
storing, in the printer driver 108, the new profile which has been
formed in the new profile forming and processing section 402.
[0050] Next, an outline of a profile forming process will be
described with reference to the user interfaces (UIs) of FIGS. 3
and 5 and the flowchart of FIG. 2. FIG. 5 illustrates one example
of a printing setting UI used to make settings on the printer side
when a "print" menu is selected from a menu list of the application
107. A method for operating a printing setting screen when a
printer user wants to print an image on paper supported in the
maker's specifications will now be described. On a printing setting
screen 501, the printer user performs a series of operations of
selecting a paper category 502, printing quality 503, and a
matching method 504, and pressing a "print" button 505. When the
user wants to print an image on other paper than that supported in
the maker's specifications, setting operations on the printing
setting screen 501 are performed as follows. In setting of the
paper category 502, an option item "paper not adapted" is selected.
When the option item "paper not adapted" is selected, the "print"
button 505 is made ineffective. Thereafter, the user selects the
printing quality 503 and the matching method 504 and then presses a
"newly form profile" button 506. A UI screen, shown in FIG. 3, for
setting conditions to form a profile is opened in response, and the
processing shown in the flowchart of FIG. 2 is started.
[0051] In step S201, when a proper item is selected from each of a
"series selection" box 301 and a "model/paper selection" box 303 of
the UI shown in FIG. 3, the model name of the printer employed by
the user is obtained. More specifically, in this process, the user
first selects the printer, which is employed by the user, in the
"series selection" box 301 of the UI shown in FIG. 3 by checking
one of radio buttons 302. Next, on a pull-down menu 304 in the
"model/paper selection" box 303, the user selects one from a list
of models corresponding to the printer series selected by checking
one of the radio buttons 302. In step S202, on a pull-down menu 305
in the "model/paper selection" box 303 of the UI shown in FIG. 3,
the user selects paper belonging to the same category as the paper
that the user wants to use. The selection of paper is performed by
displaying, to the user, a list of paper categories corresponding
to the printer series, which has been selected by checking one of
the radio buttons 302, so that the user can select one desired
paper category on a pull-down menu. To that end, the pull-down menu
305 of the UI shown in FIG. 3 displays a list of the paper
categories corresponding to the printer model which has been
selected by the user from the radio buttons 302 and the pull-down
menu 304. FIG. 6 shows one exemplary list of the paper categories.
In step S203, when a "detailed setting" button 319 for the light
source, shown in FIG. 3, is pressed, a UI shown in FIG. 18 is
displayed. In the UI of FIG. 18, the user selects "domestic
(fluorescent lamp)", "standard light source", or "detailed setting"
in a left column of the displayed screen, and then proceeds to a
right column of the displayed screen. When the user selects
"domestic" in the left column of the screen, the user is further
prompted to select one light source from among "natural color",
"daylight color", and "incandescent lamp-like color" in the right
column. With that selecting operation, the corresponding light
source information stored in the light source information database
111 is obtained. Similarly, when the user selects "standard light
source", the user is further prompted to select one light source
from among "A", "C", "D50", "D65", "F10", etc. With that selecting
operation, the corresponding light source information is obtained.
When the user selects "detailed setting" on the left side of the
screen of FIG. 18, the user is further prompted to enter the model
number of an illuminator that is expected to be used as the light
source when the user observes a print. With that selecting
operation, the corresponding light source information stored in the
light source information database 111 is obtained. In step S204, a
profile corresponding to the printer and paper characteristics
obtained in steps S201 and S202 (more specifically, the name of the
printer series, the model name, the category of paper to be used in
the printing, the printing quality, and the matching method) is
obtained from the profile server 105, shown in FIG. 1, which stores
various profiles in advance. In step S205, a light source
conversion process with the existing profile is executed by using
the light source information obtained in step S203 and the existing
profile obtained in step S204. In the light source conversion
process of step S203, values of CIE XYZ are calculated based on the
following formulae (1) to (3) by using a spectral distribution
S(.lamda.) obtained in step S203, a spectral reflectance R(.lamda.)
in the existing profile obtained in step S204, and color matching
functions x(.lamda.), y(.lamda.) and z(.lamda.) defined in Japanese
Industrial Standard JIS Z8782:
X=.intg.R(.lamda.)S(.lamda.)x(.lamda.) . . . (1)
Y=.intg.R(.lamda.)S(.lamda.)y(.lamda.) . . . (2)
Z=.intg.R(.lamda.)S(.lamda.)z(.lamda.) . . . (3) From those values
of X, Y and Z, values of CIE LAB are calculated based on the
conversion formulae defined in JIS Z8729.
[0052] In step S206, when the user presses a "print out
determination patch" button 311 in FIG. 3, a process of determining
the total colorant amount under the printing conditions requested
by the user is started. Details of the total colorant amount
determining process will be described later with reference to FIG.
10. In step S207, when the user presses a "form profile" button 315
in FIG. 3, a color separation profile optimum for the total
colorant amount obtained in step S204 is formed. Details of this
color separation profile forming process will be described later
with reference to a flowchart of FIG. 13. In step S208, a color
matching profile for executing color gamut conversion similar to
that executed by the existing profile is formed by using the color
separation profile which has been formed in step S207. Details of
this color matching profile forming process will be described later
with reference to FIG. 14. In step S209, the profiles formed in
steps S207 and S208 are registered in the printer driver 108.
[0053] With the processing described above, the profiles for a new
category of paper can be formed.
<Total Colorant Amount Determining Process>
[0054] Details of the total colorant amount determining process in
step S206 of FIG. 2 will now be described with reference to the
flowchart of FIG. 10 and patches shown in FIGS. 11 and 12.
[0055] In step S1001, basic information represented by a primary
color correction table, binary conversion parameters, a maximum
value of the colorant amount for paper (printing medium), etc. is
obtained based on the existing profile information which has been
obtained in step S204. In step S1002, a total colorant amount
determining patch for determining the total colorant amount for the
paper is formed based on the basic information obtained in step
S1001, and this patch is printed on the paper on which the user
wants to print an image by the printer 103. As shown in FIG. 11, by
way of example, the total colorant amount determining patch is
represented by an image made up of non-printed portions and printed
portions, each of those portions having a certain width, a certain
level of the total colorant amount, and a different resolution
(different number of lines). The printed portions and the
non-printed portions are alternately positioned in a straight line.
The total colorant amount determining patch printed here is not
limited to the patch shown in FIG. 11. As another example, as shown
in FIG. 12, the total colorant amount determining patch can also be
printed in an image made up of non-printed portions arranged in a
crossed shape and printed portions, each of those portions having a
certain width and a certain level of the total colorant amount. The
image can be printed in any desired shape so long as the printed
portions and the non-printed portions are adjacent to each other.
While the total colorant amount is shown in four levels in each of
FIGS. 11 and 12, the number of levels is not limited to four.
[0056] Next, in step S1003, a maximum total colorant amount for the
paper on which the user wants to print an image is input based on
the total colorant amount determining patch which has been printed
in step S1002. In the case using the patch shown in FIG. 12, for
example, the maximum total colorant amount is determined by the
user reading, from the printed result of the total colorant amount
determining patch, a limit at which the user can clearly discern
the image in the non-printed portions in the crossed shape. The
user enters the determined maximum total colorant amount in a text
box 312, shown in FIG. 3, and then presses a "decision" button
313.
[0057] When the maximum total colorant amount is determined, it is
better to prepare an index indicating how much a cross-shaped
character is deformed. Also, the index can be formed so as to
separately determine the degree of deformation between the case of
printing text and the case of printing a photograph. Further, the
maximum total colorant amount can also be automatically determined.
In such a case, the printed patch image is read by the scanner 106,
for example, and the non-printed portions in the crossed shape,
shown in FIG. 12, are extracted and used to make the determination.
As an alternative, the maximum total colorant amount can be
automatically determined by mounting a sensor (not shown), such as
a CCD, on the printer 103, reading the printed patch shown in FIG.
11, preparing sharpness data for each colorant amount, and by
determining the maximum total colorant amount based on the
sharpness data. A determination criterion in that case can be
changed depending on whether a printing target is text or a
photograph. For example, a threshold can be set for each level of
resolution corresponding to each of the text and the photograph,
and the resolution can be changed in evaluating each of the text
and the photograph.
[0058] The total colorant amount determining process can be
executed as described above.
<Color Separation Profile Forming Process>
[0059] Details of the color separation profile forming process in
step S207 will now be described with reference to FIG. 13.
[0060] In step S1301, the existing color separation profile
corresponding to the printing conditions requested by the user
(such as the model, the paper category, the printing quality, and
the matching method) is obtained based on the existing profile
information which has been obtained in step S204. Herein, the term
"color separation profile" means a lookup table in which an ink
amount is described for each grid point distributed over a grid in
the form of an RGB three-dimensional cube. In step S1302, color
separation values are calculated on contour lines while keeping the
total colorant amount calculated in step S206 and the
characteristics of the existing color separation profile obtained
in step S1301. Herein, the term "contour lines" means a W-Bk line,
a R-Bk line, a G-Bk line, a B-Bk line, a C-Bk line, a M-Bk line, a
Y-Bk line, a R-W line, a G-W line, a B-W line, a C-W line, a M-W
line, and a Y-W line which interconnect respective colors
represented by the apexes of the RGB three-dimensional cube.
Adjustment of the colorant amounts in step S1302 is performed, for
example, by placing more importance to dark ink when the user
intends to widen a color reproduction range, and by placing more
importance to light ink when the user intends to reduce graininess.
In step S1303, an interpolation process is executed to calculate a
color on each grid point of the RGB three-dimensional cube through
an interpolation by using the color separation values on the
contour lines which have been calculated in step S1302. In step
S1304, the total colorant amount in the color separation profile
formed through the processing up to step S1303 is corrected. More
specifically, the correction process of adjusting the total
colorant amount is executed such that the total colorant amount
corresponding to the color separation values represented by the
respective grid points in the color separation profile, which has
been formed through the processing up to step S1303, is held within
the total colorant amount calculated in step S206. Note that the
correction method is not limited to the above-described one and
other general correction methods can be used as an alternative. In
step S1305, a smoothing process is executed to smooth the color
separation profile which has been formed through the processing up
to step S1304. In step S1306, it is checked whether the total
colorant amount corresponding to the color separation values
represented by the respective grid points in the color separation
profile, which has been formed through the processing up to step
S1305, exceeds the total colorant amount calculated in step S206.
If so, the processing flow is returned to step S1304, and if not
so, the processing flow advances to the next process (step
S1307).
[0061] Thus, based on the existing profile information which has
been obtained in step S204, the color separation profile
corresponding to the printing conditions requested by the user
(such as the model, the paper category, the printing quality, and
the matching method) can be obtained.
[0062] In step S1307, when the user presses a "print out patch"
button 316 shown in FIG. 3, a patch for obtaining the color
reproduction characteristic is printed using the formed color
separation profile in order to form a color matching profile
described later. The patch can be prepared as digital data which
represents RGB in 9 stages for each of RGB (729 colors in total),
for example, and which can provide the color reproduction
characteristic under the environment where the user wants to print
an image.
<Color Matching Profile Forming Process>
[0063] Details of the flow of the color matching profile forming
process in step S208 will now be described with reference to FIG.
14.
[0064] In step 1401, the existing color matching profile
corresponding to the printing conditions requested by the user
(such as the model, the paper category, the printing quality, and
the matching method) is obtained based on the existing profile
information which has been obtained in step S204. The term "color
matching profile" means data given in the form of calorimetric data
Lab when digital data RGB sent to the printer is printed under the
above-described printing conditions, more specifically Lab values
corresponding to the printing result of RGB data in 17 stages for
each of RGB (4913 colors in total). In step S1402, when the user
presses a "read calorimetric data" button 317 shown in FIG. 3, the
Lab data is obtained by measuring the patch, which has been
previously printed in step S1307 of FIG. 13, with the input device,
e.g., the scanner 106, a calorimeter (not shown), or the like. In
step S1403, when the user presses a "form profile" button 318 shown
in FIG. 3, a color gamut compression process is executed such that
the colors reproduced by the existing color matching profile, which
has been obtained in step S1401, falls within the color
reproduction range to be reproduced under the user-requested
printing conditions which have been obtained in step S1402. The
color gamut compression process described here is merely one
example and the present invention is not limited to the
above-described process. Depending on the demanded accuracy and
purpose, the color gamut compression process can be modified, for
example, such that the colors in the input color gamut are
converted to colors which minimize color differences with respect
to the colors within the printing color gamut. In step S1404, a
color matching profile is formed by using the result of the color
gamut compression process obtained in step S1403 and the
user-requested printing conditions obtained in step S1402.
[0065] While this first embodiment is described as using Lab as a
color space for processing, the present invention is not limited to
the use of Lab. The color space can be of course changed depending
on the demanded accuracy and purpose.
[0066] Thus, based on the existing profile information, the color
matching profile corresponding to the printing conditions requested
by the user (such as the model, the paper category, the printing
quality, and the matching method) can be obtained.
Second Embodiment
[0067] When professional cameramen and graphic artists produce
works using a large format printer (denoted by 805 in FIG. 8), the
paper cost is greatly increased and the printing time prolonged if
several tens of prints are repeatedly printed on a trial-and-error
basis. With the second embodiment of the present invention, such a
problem can be avoided through the steps of first producing a
scaled-down work using a small format printer (denoted by 803 in
FIG. 8), and then forming a profile for the large format printer so
as to provide the same color reproduction as that obtained with the
small format printer.
[0068] The second embodiment will be described below with reference
to FIG. 8.
[0069] FIG. 8 is a block diagram of an image printing system
according to a second embodiment of the present invention. The
image printing system includes a PC 801 for executing control,
which is the same as the PC used in the image printing system
according to the first embodiment. Also, the image printing system
includes an image display apparatus 802, such as a monitor, for
displaying an image, and image printing apparatuses 803 and 805,
such as printers, for printing an image. Reference numeral 804
denotes a test chart printed by using the desired paper and the
printer which is demanded by a user to finally print an image,
i.e., the printer 803. Reference numeral 810 denotes a test chart
printed by using the desired paper and the printer which is
demanded by the user to print an image for testing of color
reproduction, i.e., the printer 805. The test charts used in this
second embodiment are each a print on which image data is printed
as an RGB chart (e.g., 9 stages for each of RGB and 729 colors in
total). Herein, the image data is desired to be capable of
obtaining a color reproduction characteristic under a printing
environment (including a printer and paper) in which the user wants
to print an image. The image printing system further includes an
image input device 806, such as a scanner, for inputting an image.
The control PC 801 incorporates an image processing application 807
for displaying and editing an image on the PC 801, a printer driver
808 for controlling and driving the printers 803 and 805, and an OS
(Operating System) 809 for operating the PC 801 itself. The
processing flow in this second embodiment differs from that in the
first embodiment as follows. While the existing profile is obtained
from the profile server 105 in the first embodiment, it is obtained
from the printer 805 via the PC 801 in this second embodiment. With
such a feature, this second embodiment can form a profile for the
printer 803, which can provide the same color reproduction as that
obtained by the printer 805.
[0070] Thus, the paper cost and the printing time can be saved in
comparison with the case where several tens of prints are
repeatedly printed on a trial-and-error basis by a large format
printer.
Third Embodiment
[0071] A third embodiment of the present invention can easily form
a profile capable of providing the color reproduction
characteristic of paper, which is ordinarily employed by a user,
when another category of paper is employed. The third embodiment
will be described below with reference to FIG. 9.
[0072] FIG. 9 is a block diagram of an image printing system
according to a third embodiment of the present invention. The image
printing system includes a PC 901 for executing control, which is
the same as the PC used in the image printing system according to
the first embodiment. Also, the image printing system includes an
image display apparatus 902, such as a monitor, for displaying an
image, and an image printing apparatus 903, such as a printer, for
printing an image. Reference numerals 904 and 905 denote test
charts printed by using the printer 903 in combination with
different categories (A and B) of paper, which are demanded by a
user to finally print an image. The test charts used in this third
embodiment are each a print on which image data is printed as an
RGB chart (e.g., 9 stages for each of RGB and 729 colors in total).
Herein, the image data is desired to be capable of obtaining a
color reproduction characteristic under a printing environment
(including a printer and paper) in which the user wants to print an
image. The image printing system further includes an image input
device 906, such as a scanner, for inputting an image. The control
PC 901 incorporates an image processing application 907 for
displaying and editing an image on the PC 901, a printer driver 908
for controlling and driving the printer 903, and an OS (Operating
System) 909 for operating the PC 901 itself.
[0073] The processing flow in this third embodiment differs in the
following way. While the profile is obtained from the profile
server 105 in the first embodiment and from the printer 805 via the
PC 801 in the second embodiment, it is obtained from the test chart
904 printed using the paper A in this third embodiment. With such a
feature, this third embodiment can easily form a profile capable of
providing the color reproduction characteristic of the paper A
(corresponding to the test chart 904), which is ordinarily employed
by the user, when another category of paper B (corresponding to the
test chart 905) is employed.
Other Embodiments
[0074] The present invention can be practiced in the form of a
system comprising a plurality of units (e.g., a host computer, an
interface device, a reader, and a printer), or a single unit (e.g.,
a copying machine or a facsimile).
[0075] While the above embodiments have been described on the
assumption that the printing medium is paper, the printing medium
is not limited to paper. An OHP or a CD-ROM having a label surface
can also be used as the printing medium.
[0076] While the above embodiments have been described in
connection with a printer using ink as a colorant, the application
field of the present invention is not limited to such a printer.
The present invention can also be applied to, for example, a
copying machine using toner as a colorant.
[0077] The present invention can also be practiced by supplying a
storage medium, which stores program code of software for
implementing the functions of the above-described embodiments, to a
system or an apparatus, and by causing a computer (CPU or MPU) in
the system or the apparatus to read and execute the program code
stored in the storage medium. In that case, the program code read
out of the storage medium serves in itself to implement the
functions of the above-described embodiments, and therefore the
storage medium storing the program code constitutes the present
invention.
[0078] Storage media for supplying the program code can be, e.g., a
flexible disk, a hard disk, an optical disk, a magneto-optical
disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card,
or a ROM.
[0079] Also, the present invention involves not only the case where
the functions of the above-described embodiments are implemented by
the computer executing the read program code, but also the case
where an operating system or the like running in the computer
executes a part of actual processing in accordance with
instructions from the program code and implements the functions of
the above-described embodiments through the processing executed by
the operating system or the like.
[0080] Further, the program code read out from the storage medium
can be written in a memory which is provided in a function
extension board inserted in the computer or in a function extension
unit connected to the computer, and a part or the whole of the
actual processing can be executed by a CPU, which is incorporated
in the function extension board or the function extension unit, in
accordance with the instructions from the program code. Thus, the
present invention involves the case where the functions of the
above-described embodiments are implemented through the processing
executed by the CPU.
[0081] While the present invention has been described with
reference to exemplary embodiments, it is to be understood that the
invention is not limited to the disclosed exemplary embodiments.
The scope of the following claims is to be accorded the broadest
interpretation so as to encompass all modifications, equivalent
structures and functions.
[0082] This application claims the benefit of Japanese Patent
Application No. 2006-215858 filed Aug. 8, 2006, and No. 2007-170230
filed Jun. 28, 2007 which are hereby incorporated by reference
herein in their entirety.
* * * * *